There are a variety of methods that exist today to deliver fluids. Within those, there are three broad prior art categories of fluid delivery types. One prior art category would include mechanical systems, such as brushes, pads, and foams. A second category would include pressurized or electromagnetic driven systems which are generally active. A third category would include capillary (or wick) based systems which are generally passive.
Within the first mechanical systems category, where the system holds and releases fluids by mechanical means via brushes, pads and/or foams, the prior art typically includes products such as paint brushes, foam applicators for cosmetics, and other brush-based fluid delivery systems.
A drawback of using fluid delivery systems within this category is that generally, there is lack of consistency in fluid output and they require continuous refill.
One common class within the second pressurized delivery category is a pump-based system which may typically include a peristaltic pump and/or other electrical, mechanical, electromagnetic or pressure driven devices to deliver a specific or defined level of fluid or fluid. A well-known product founded on pump-based principles would be a paint system that continuously dispenses paint into a roller such as the commercially available Wagner paint sprayer device. Other examples include squirt gun type tank sprayers used in fertilizer or bug spraying.
A drawback of this type of pump-based delivery system is that it is active and hence, requires energy to operate, thereby making it a relatively costly solution for a desired low cost or mass marketed product.
Another drawback of fluid delivery with a pump is that the system is either always on or would require actuation, thus, while the system may provide greater versatility it may not deliver the specific dose for a desired application, a critical factor to functionality or product aesthetics.
The third category of fluid delivery includes capillary based systems. Prior art capillary systems would include sintered powders, filamentous, foam or fiber based systems.
Some common examples of capillary system products would be wick-based air freshener fragrance-delivery products or some ink jet printer delivery products. The fiber based systems use bundles or other structures that are physically attached to each other. Some examples of these are: felt tip pens, magic markers, porous dome applicators (e.g. sintered pressed powder). However, as with other prior art solutions, fiber bundles are not necessarily consistent in the amount of product delivered and attempts to solve that problem by varying the applicator size adds difficulty. Furthermore, multiple uses of these systems can result in cloggage over time rendering inconsistent delivery of material to the desired dose.
The gradient or compressed foam described for fuel cells in U.S. Pat. No. 6,994,932 requires both a pump and capillary-based system, increasing the cost and complexity of the final device. Additionally, a limitation of the system described therein is that in its application to fuel cells for electronic devices it is a self-contained system, i.e. not open to the environment due to volatility of the fuel fluid.
Although these prior art systems described above function properly, some have inconsistent fluid delivery, some require energy, some are closed to the environment and there can be great variability in fluid delivery due to manufacturing, inconsistencies from product to product, and/or changes within a given product over time.
Further, many prior art systems are limited as they do not provide a continuous, tailored and precise fluid delivery system nor the capability of using a varying number and type of fluids, such as aqueous water or non-aqueous or oil based fluids.
A need exists to deliver fluids passively, independently of orientation and gravity, open to the environment and with the ability to tailor the amount of fluid delivered to a unit of area, thereby reducing cost and increasing effectiveness.
A further need exists to deliver any types of fluid, or a plurality of fluids or formulations directly to any type of surface (i.e. hard, soft, fabric, skin, hair, teeth) thereby covering many application areas.